Dual-diaphragm distributor

ABSTRACT

A vacuum motor having two independently mounted and movable flexible diaphragms mounted in a common housing and partitioning the housing into fluid chambers, one of the diaphragms having a limited movement and at times limiting the movement of the other diaphragm, the other being connected to a means to be actuated; and, of which the following is a specification.

United States Patent 687,519, Dec. 4, 1967, now abandoned.

DUAL-DIAPHRAGM DISTRIBUTOR Primary Examiner-Mark M. Newman Assistant Examiner Ronald B. Cox Attorneys-John R. Faulkner and Robert E. McCollum 8 Claims, 8 Drawing Figs,

U.S.Cl 123/117A Cl 1 5/04 ABSTRACT: A vacuum motor having two independently Field of Search 123/1 17.1, mounted and movable fl ibl diaphragms mounted in a 97 B mon housing and partitioning the housing into fluid chambers, one of the diaphragms having a limited movement and at times References C'ted limiting the movement of the other diaphragm, the other being UNITED STATES PATENTS connected to a means to be actuated; and, of which the follow- 2,827,889 3/1958 Smitley 123/1 17 ing is a specification.

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' ATTORNEYS exhaust emission controls point out the desirability of a retarded ignition timing at engine idle and deceleration conditions asv well as a rapid shift to normal timing at all other engineoperating conditions. The retarding of the ignition timing during idle and deceleration produces a marked reduction in engine exhaust hydrocarbon emissions, whereas a rapid shift to normal ignition timing allows starting ease and minimum loss of engine performance and economy. I

Devices are known in the prior art for automatically advancing or retarding the engine distributor advance plate to control the spark timing. However, these devices generally.

require a plurality of separate and remote elements, which increase the' overall costof the engine and complexity of the system.

The invention'relates to a dual-diaphragm vacuum motor assembly within a single housing that operates automatically in conjunction with other controls to properly regulate the movement of the ignition distributor spark advance and retard mechanism to provide the desired retarding or advancing of the spark at all engine operating conditions.

It is an object of the invention, therefore, to provide adualdiaphragm fluid motor assembly having a pair of coaxially mounted and axially spaced annular diaphragms mounted within a'single housing for independent movement at time and-conjointmovement at other times.

It isfanother object of the invention to provide a vacuum motor assembly for an ignition distributor that automatically advances or retards the ignition timing as a function of the engine operating conditions as determined by the change in flow of the air-fuel mixture through the carburetor, and by the change in intake manifold vacuum of the engine.

- It'is still a further object of the invention to provide a vacuum motor assembly consisting of two coaxially mounted, independently movable, flexible diaphragms mounted within a common housing to partition the housing into separate fluid or vacuum chambers; one being connected to a portion of an engine carburetor above the throttle valve, the other being connected to the carburetor below the throttle valve at a point leading to the intake manifold; one of the diaphragms being connected to the distributor advance plate and cooperating at times with the other diaphragm to have a limited movement in one direction while being essentially freely movable in the opposite direction; the other diaphragm having a limited movement in both directions to at times control the movement of the spark advance plate while at other times being ineffective to provide such control.

Other objects, features and advantages of the invention will become more apparent upon reference to the succeeding detailed description thereof, and to the drawings illustrating the preferred embodiment thereof, wherein F IG. l illustrates, schematically, an internal combustion engine spark timing control mechanism embodying the invention;

FIG. 2 is a cross-sectional view of the vacuum motor illustrated in FIG. 1;

FIGS. 3 and 4 are end elevational views, with parts broken away and in section, taken on planes indicated by and viewed in the direction of the arrows 3-3 and 4-4, respectively, of FIG. 2; and,

FIGS. 5, 6 7, and 8 are cross-sectional views similar to FIG. 2 illustrating the parts therein in various operative positions corresponding, respectively, to engine-starting and wide-open throttle positions, engine-idling position, part throttle operation, and engine deceleration operation.

FIG. 1 shows, schematically, those portions of an internal combustion engine that are interrelated with the vacuum motor assembly of the invention to provide for an automatic retardation advancement of the engine distributor ignition timing. More specifically, 10 indicates, in general, an ignition distributor of the centrifugal advance type having an ignition timing advance plate 12. The plate surrounds the conventional rotor cam 14 an is pivoted for movement abouta point 16 fixed to the stationary distributor housing, not shown. Rotor cam 14 cooperates with a set of breaker points 18 by means of an actuator 20 secured to one arm of the breaker points set, as shown. Advance plate 12 is pivotally secured at 22 to a reciprocatable actuating rod 24 that is adapted to be moved in a manner to be described by the dual-diaphragm vacuum motor assembly 26 embodying the invention.

At the opposite sides of the vacuum motor assembly is shown a portion 28 of a carburetor of the conventional downdraft type. It has the usual air-fuel induction passage 30 containing a fixed area venturi 32 and a conventional throttle valve 34 pivotally mounted on a portion of the carburetor housing to control flow from passage 30 to the engine intake manifold 36.

In general, vacuum motor assembly 26 includes two flexible diaphragms, each of which forms a fluid or vacuum chamber with the housing to provide various control movements of the advance-plate-actuating rod 24. The chamber closest to the distributor is connected by a hose or line 38 directly to the vacuum of the engine intake manifold through carburetor port 40 that opens into the carburetor below throttle valve 34. It will be clear, of course, that port 40 could be located to open directly into intake manifold 36. The other vacuum motor chamber is connected by a hose or line 42 through a shuttlevalve-controlled mechanism 44 and a port 46 to a point in carburetor induction passage 30 above throttle valve 34, it is in its idle position.

Shuttle valve 44, referred to as a deceleration control valve, or decel valve, is controlled in its movement by the level of the intake manifold vacuum, a branch line 47 connecting the intake manifold vacuum in line 38 to act on the valve. Below a predetermined intake manifold vacuum, the valve connects carburetor port 46 to vacuum motor hose 42, vacuum above this point moving the shuttle valve to connect intake manifold vacuum in branch line 47 to hose 42.

Decel valve 44, in this case, comprises a reciprocable valve alternately seatable against two ports 48 and 49 as a function of the differential force between intake manifold vacuum in line 47 applied to one side of a diaphragm 50 opposed by the force of a tension spring 51. As stated previously, the valve determines whether carburetor port pressure in line 46 or intake manifold vacuum in line 47 will be applied to the vacuum motor chamber connected to hose or line 42.

The manifold vacuum level necessary to actuate the shuttle valve, in this case, would occur only during deceleration operation of the engine, at which time a higher than normal intake manifold vacuum is present in the system. 7

FIGS. 2 through 4, which are essentially to scale, show the details of construction of vacuum motor assembly 26. More specifically, the vacuum motor has an outer housing 52, that includes a belllike, hollow, left-hand portion 53, and a donutshaped, right-hand portion 54, the latter having a steppeddiameter central opening 56. Axially between the two housing portions is a ringlike spark advance stop plate 58 contiguous to a ringlike spark retard stop plate 60. The latter has a stepped inner diameter 62 defining, with stop plate 58, an annular groove 64. Projecting into and axially movable within groove 64 is the bent edge 66 of a washerlike diaphragm retainer 68. The latter retainer, together with a cup-shaped apertured retainer 70, is clamped to an annular flexible diaphragm 72 having a central aperture 74. The diaphragm extends across the hollow interior of the housing and is sealingly mounted at its outer edge between stop plate 60 and the flange on housing portion 54. A locknut-type keeper member 76 sealingly clamps the diaphragm inner edge against a shoulder on housing portion 54, with a rubber washer between, as shown.

A spring 78 normally biases the diaphragm 72 to the position shown locating flange edge 66 against the face of advance stop plate 58. The diaphragm, together with the walls of housing portion 54, defines a fluid or vacuum chamber 80. Chamber 80 is connected to intake manifold vacuum hose 38, as best seen in FIG. 4.

A second flexible annular diaphragm 82 is sealingly mounted between housing portions 53 and stop plate 58, and extends across the housing to define with it a fluid or vacuum chamber 84. Chamber 84, as best seen in FIG. 3, is connected to hose 42, leading to shuttle valve 44 in FIG. 1. The two housing portions and stop plates and diaphragms are fixedly secured together by means of an annular cap plate 85.

Distributor advance-plate-actuating rod 24 is fixedly secured to what will be termed primary diaphragm 82 by means of two Cup-shaped 86 and 88 so that movement of the diaphragm in either direction will cause a corresponding movement of the distributor advance plate 12 (FIG. 1). The radially outermost bent edge 90 of plate 88 at times is adapted to abutthe inner edge of what will be termed the secondary diaphragm stop plate 68 to limit' movement ofthe primary diaphragm in one direction, for a purpose to be described later. A spring 92 normally biases the primary diaphragm 82 and rod 24 to the right to seat abut edge 90 against plate 68.

v The forces of secondary chamber spring 78 is chosen to be greater than that of spring 92 so that, all other conditions being equal, the secondary stop member 66 is positioned I against the'face of the advance plate 58, as shown.

The invention will be more fully understood by reference to FIGS. 5 through 8 illustrating, progressively, the various modes of operation. FIG. 5 illustrates the operation when the internal combustion engine either is off and ready to start, or operating at wide-open throttle conditions. Taking first the engine off or starting conditions of operation, and referring also to. FIG. I; with the engine ofi, there is no airflow through the carburetor into the intake manifold, and the pressure level at both ports 46 and 40 and in both hoses 42 and 38 is atmospheric. Thus, atmospheric pressure forces acting on diaphragms 72 and 83 permit secondary diaphragm spring 78 to seat stop flange 68 against the face of advance plate 58, the primary advance spring 92 seating primary diaphragm 82 as shown with the flange edge 90 against stop flange 68. Actuating rod 24, therefore, is positioned at this time to provide the spark timing desired for starting of the engine.

It will also be seen that the position shown in FIG. 5 corresponds to wide-open throttle operating conditions. That is, at wide-open throttle, intake manifold vacuum is essentially at atmospheric pressure. Also, throttle valve 34 is rotated wide open and port 46, thereofe, also, is essentially at atmospheric pressure; therefore, the same pressure conditions exist in the primary and secondary diaphragm chambers 84 and 80 as at engine starting, and actuating rod 24 remains in the same position shown and described.

Assume now that the engine has been started, and throttle pedal '34 is in the'closed position shown in FIG. 1, for idlespeed operation. Referring to FIG. 6, intake manifold vacuum at this time is high and reflected in the hose 38 (FIG. 4) to secondary diaphragm chamber 80. The manifold vacuum is sufficient at this time to overcome the force of spring 78 and pull diaphragm 72 to the right until the stop 66 abuts the face of retard stop plate 60. Simultaneously, the intake manifold normal manner. Simultaneously, the intake manifold vacuum acting in the secondary diaphragm chamber 80 has decreased sufficiently to permit spring 78 to move secondary diaphragm 72 to the left of the position indicated, that is, the advance position'moving stop member 66 against the face of advance" plate 58. Thus, under these circumstances, the primarydiaphragm has moved independently of secondary diaphragm 72 to provide ignition-timing adjustment in a normal manner. FIG. 8 illustrates the positions of the parts during an enginedecelerating operating condition. At this time, the intake manifold vacuum increases to a level where decel valve 44 is actuated to cause manifold vacuum to be directed to primary diaphragm' chamber 84 instead of carburetor spark port pressure or vacuum. Therefore, at this time, a high-intake manifold vacuum will pull primary diaphragm 82 to the left'to the position indicated in FIG. 8, and move the advance-plateactuating rod 24 to advance the timing an amount dependent upon the level of the intake manifold vacuum. Simultaneously,

high-intake manifold vacuum acting in the secondary diaphragm chamber 80 maintains the secondary diaphragm stop flange 66 against the retard face of plate 60, as shown. Again the movement of the primary diaphragm is made independent of the movement of the secondary diaphragm.

From the foregoing, it will be seen that the invention provides a vacuum motor assembly or construction that permits independent mounting of the two diaphragms in a common housing for independent movement at times with respect to each other while at other times providing a limited movement of one relative to the other.

While the invention has been shown and described in its preferred embodiment in the drawings, it will be clear to those skilled in the arts to which it pertains that many modifications and changes may be made thereto without departing from the scope of the invention.

I claim:

1. A spark timing apparatus for an internal combustion engine comprising, an engine-throttle-controlled carburetor air/fuel, induction passage having a pressure-sensing port located upstream of the throttle valve when in its idle-speed 1 position, an engine intake manifold vacuum-sensing port, a

vacuum being below the level sufficient to actuate decel'valve 44, and carburetor spark port 46 being essentially at atmospheric pressure, atmospheric pressure is applied through hose or line 42 to primary diaphragm 82 to move it to the right until it is stopped by abutment against the secondary diaphragm stp 68. Thus, actuating rod 24 will have been moved to the maximum retard position shown.

F IG; 7 illustrates the positions of the parts during part-throttle engine operation. More specifically, when the throttle lever 34 in FIG. 1 is rotated counterclockwise .past port 46 to prospark timing distributor breaker plate movable in opposite directions between maximum and minimum positions to operably advance or retard the engine spark timing, vacuum servo means comprising a housing having first and second axially spaced flexible annular diaphragms therein dividing said housing into firstand second varying pressure chambers, means connecting said first diaphragm to said breaker plate to move the latter, first and second conduit means operablyconnecting said first and second chambers respectively to said carburetor upstream and manifold vacuum-sensing ports, the increase in upstream port vacuum during movement of the throttle valve from its idle speed towards full-throttle position efiecting normal spark advance timing movement of said first diaphragm towards a maximum spark advance position, the increase in the manifold vacuum port vacuum during movement of the throttle valve towards its-closed-throttle position urging said second diaphragm in a spark timing retard the higher idle-speed vacuum level in said manifold vacuum port compared to that in the upstream port effecting movement of said second diaphragm against one of said stop means and the engagement of said first diaphragm against said second diaphragm to position said breaker plate for a minimum position providing maximum spark retard, the opening of said throttle valve reducing the vacuum differential between said ports and effecting movement of said second diaphragm to its other stop means and said first diaphragm in a spark advance direction freely away from said second diaphragm.

2. A spark timing apparatus as in claim 1, including stop means in the path of spark advance movement of said first diaphragm to limit the spark advance timing adjustment.

3. A spark timing apparatus as in claim 1, said members being coaxially mounted and axially spaced from each other for independent axial movement at times of each of said members.

4. A spark timing apparatus as in claim 1, said spring means each having a preload of a different value.

5. A spark timing apparatus as in claim 3, said second diaphragm comprising a disk with a central aperture, said first diaphragm comprising a disk operatively connected to said breaker plate and movably projecting through the aperture of said second diaphragm.

6 A spark timing apparatus as in claim 1, including shuttle valve means operably connected between said first and second conduit means and spring biased to one position and operably movable to a second position above a predetermined vacuum level by the vacuum in said second conduit means acting thereagainst to alternately connect said first chamber to the vacuum in said upstream port through said first conduit means or to the vacuum in said downstream port through said second conduit means, whereby above said predetermined vacuum level in said downstream port said first diaphragm will be moved to a maximum spark advance position by the vacuum in said second conduit means.

7. A spark timing apparatus for an internal combustion engine comprising, an engine-throttle-controlled carburetor air/fuel induction passage having a pressure-sensing port located upstream of the throttle valve when in its idle-speed position, an engine intake manifold vacuum-sensing port, a spark timing distributor breaker plate movable in opposite directions between maximum and minimum positions to operably advance or retard the engine spark timing, vacuum servo means comprising a housing having first and second axially spaced fiexible annular diaphragms therein dividing said housing into first and second varying pressure chambers, means connecting said first diaphragm to said breaker plate to move the latter, first and second conduit means operably connectingsaid first and second chambers respectively to said carburetor upstream and manifold vacuum-sensing ports, the increase in upstream port vacuum during movement of the throttle valve from its idle speed towards full-throttle position effecting normal spark advance timing movement of said first diaphragm towards a maximum advance position, and first and second spring means respectively biasing said first and second diaphragms in spark timing retard and advance directions whereby under no vacuum engine start conditions said breaker is positioned by said spring means to condition said engine for starting at a spark setting above the minimum, and is subsequently movable during engine idle conditions by engine manifold vacuum acting against said second diaphragm to a minimum spark setting position.

8. A spark timing'apparatus for an internal combustion engine comprising, an engine-throttle-controlled carburetor air/fuel induction passage having a pressure-sensing port located upstream of the throttle valve when in its idle-speed position, an engine intake manifold vacuum-sensing port, a spark timing distributor breaker plate movable in opposite directions between maximum and minimum positions to operably advance or retard the engine spark timing, vacuum servo mean corn rising a housin having first and second axially spaced flexr le annular drap ragms therein dividing said housing into first and second varying pressure chambers, means connecting said first diaphragm to said breaker plate to move the latter, first and second conduit means operably connecting said first and second chambers respectively to said carburetor upstream and manifold vacuum-sensing ports, the increase in upstream port vacuum during movement of the throttle valve from its idle speed towards full-throttle position effecting normal spark advance timing movement of said first diaphragm towards a maximum position providing maximum spark advance, the increase in the manifold vacuum port vacuum during movement of the throttle valve towards its closed-throttle position urging said second diaphragm in a spark timing retard direction, and first and second spring means respectively biasing said first and second diaphragm in spark timing retard and advance directions whereby under no vacuum engine start conditions said breaker plate is positioned by said spring means to condition said engine for starting at a spark setting above the minimum, and is subsequently movable during engine idle conditions by engine manifold vacuum acting against said second diaphragm to a minimum spark position, said second diaphragm being operably engaged at times by said first diaphragm to variably limit spark timing retard movement of said first diaphragm as a function of the positions of said second diaphragm as determined by the vacuum differential between said upstream and manifold vacuum ports. 

1. A spark timing apparatus for an internal combustion engine comprising, an Engine-throttle-controlled carburetor air/fuel induction passage having a pressure-sensing port located upstream of the throttle valve when in its idle-speed position, an engine intake manifold vacuum-sensing port, a spark timing distributor breaker plate movable in opposite directions between maximum and minimum positions to operably advance or retard the engine spark timing, vacuum servo means comprising a housing having first and second axially spaced flexible annular diaphragms therein dividing said housing into first and second varying pressure chambers, means connecting said first diaphragm to said breaker plate to move the latter, first and second conduit means operably connecting said first and second chambers respectively to said carburetor upstream and manifold vacuum-sensing ports, the increase in upstream port vacuum during movement of the throttle valve from its idle speed towards full-throttle position effecting normal spark advance timing movement of said first diaphragm towards a maximum spark advance position, the increase in the manifold vacuum port vacuum during movement of the throttle valve towards its closed-throttle position urging said second diaphragm in a spark timing retard direction, and first and second spring means respectively biasing said first and second diaphragms in spark timing retard and advance directions and towards one another, spaced stop means limiting movement of said second diaphragm in opposite directions, said second diaphragm being operably engaged at times by said first diaphragm to variably limit spark timing retard movement of said first diaphragm as a function of the positions of said second diaphragm as determined by the vacuum level in said upstream and manifold vacuum ports, the higher idle-speed vacuum level in said manifold vacuum port compared to that in the upstream port effecting movement of said second diaphragm against one of said stop means and the engagement of said first diaphragm against said second diaphragm to position said breaker plate for a minimum position providing maximum spark retard, the opening of said throttle valve reducing the vacuum differential between said ports and effecting movement of said second diaphragm to its other stop means and said first diaphragm in a spark advance direction freely away from said second diaphragm.
 2. A spark timing apparatus as in claim 1, including stop means in the path of spark advance movement of said first diaphragm to limit the spark advance timing adjustment.
 3. A spark timing apparatus as in claim 1, said members being coaxially mounted and axially spaced from each other for independent axial movement at times of each of said members.
 4. A spark timing apparatus as in claim 1, said spring means each having a preload of a different value.
 5. A spark timing apparatus as in claim 3, said second diaphragm comprising a disk with a central aperture, said first diaphragm comprising a disk operatively connected to said breaker plate and movably projecting through the aperture of said second diaphragm. 6 A spark timing apparatus as in claim 1, including shuttle valve means operably connected between said first and second conduit means and spring biased to one position and operably movable to a second position above a predetermined vacuum level by the vacuum in said second conduit means acting thereagainst to alternately connect said first chamber to the vacuum in said upstream port through said first conduit means or to the vacuum in said downstream port through said second conduit means, whereby above said predetermined vacuum level in said downstream port said first diaphragm will be moved to a maximum spark advance position by the vacuum in said second conduit means.
 7. A spark timing apparatus for an internal combustion engine comprising, an engine-throttle-controlled carburetor air/fuel induction passage having a pressure-sensing port located upstream of the throttle valve when in its idle-speed position, an engine intake manifold vacuum-sensing port, a spark timing distributor breaker plate movable in opposite directions between maximum and minimum positions to operably advance or retard the engine spark timing, vacuum servo means comprising a housing having first and second axially spaced flexible annular diaphragms therein dividing said housing into first and second varying pressure chambers, means connecting said first diaphragm to said breaker plate to move the latter, first and second conduit means operably connecting said first and second chambers respectively to said carburetor upstream and manifold vacuum-sensing ports, the increase in upstream port vacuum during movement of the throttle valve from its idle speed towards full-throttle position effecting normal spark advance timing movement of said first diaphragm towards a maximum advance position, and first and second spring means respectively biasing said first and second diaphragms in spark timing retard and advance directions whereby under no vacuum engine start conditions said breaker is positioned by said spring means to condition said engine for starting at a spark setting above the minimum, and is subsequently movable during engine idle conditions by engine manifold vacuum acting against said second diaphragm to a minimum spark setting position.
 8. A spark timing apparatus for an internal combustion engine comprising, an engine-throttle-controlled carburetor air/fuel induction passage having a pressure-sensing port located upstream of the throttle valve when in its idle-speed position, an engine intake manifold vacuum-sensing port, a spark timing distributor breaker plate movable in opposite directions between maximum and minimum positions to operably advance or retard the engine spark timing, vacuum servo mean comprising a housing having first and second axially spaced flexible annular diaphragms therein dividing said housing into first and second varying pressure chambers, means connecting said first diaphragm to said breaker plate to move the latter, first and second conduit means operably connecting said first and second chambers respectively to said carburetor upstream and manifold vacuum-sensing ports, the increase in upstream port vacuum during movement of the throttle valve from its idle speed towards full-throttle position effecting normal spark advance timing movement of said first diaphragm towards a maximum position providing maximum spark advance, the increase in the manifold vacuum port vacuum during movement of the throttle valve towards its closed-throttle position urging said second diaphragm in a spark timing retard direction, and first and second spring means respectively biasing said first and second diaphragm in spark timing retard and advance directions whereby under no vacuum engine start conditions said breaker plate is positioned by said spring means to condition said engine for starting at a spark setting above the minimum, and is subsequently movable during engine idle conditions by engine manifold vacuum acting against said second diaphragm to a minimum spark position, said second diaphragm being operably engaged at times by said first diaphragm to variably limit spark timing retard movement of said first diaphragm as a function of the positions of said second diaphragm as determined by the vacuum differential between said upstream and manifold vacuum ports. 